Crate pq_safe_kyber

Expand description

§Kyber

A rust implementation of the Kyber algorithm

This library:

Is no_std compatible and uses no allocations, suitable for embedded devices.
The reference files contain no unsafe code.
Compiles to WASM using wasm-bindgen.

§Features

If no security level is set then kyber768 is used, this is roughly equivalent to AES-196. See below for setting other levels. A compile-time error is raised if more than one level is specified. Besides that all other features can be mixed as needed:

Feature	Description
kyber512	Enables kyber512 mode, with a security level roughly equivalent to AES-128.
kyber1024	Enables kyber1024 mode, with a security level roughly equivalent to AES-256.
wasm	For compiling to WASM targets.
zeroize	This will zero out the key exchange structs on drop using the zeroize crate
std	Enable the standard library

§Usage

use pq_safe_kyber::*;

§Key Encapsulation

// Generate Keypair
let keys_bob = keypair(&mut rng);
 
// Alice encapsulates a shared secret using Bob's public key
let (ciphertext, shared_secret_alice) = encapsulate(&keys_bob.public, &mut rng)?;
 
// Bob decapsulates a shared secret using the ciphertext sent by Alice 
let shared_secret_bob = decapsulate(&ciphertext, &keys_bob.secret)?;
 
assert_eq!(shared_secret_alice, shared_secret_bob);

Higher level functions offering unilateral or mutual authentication

§Unilaterally Authenticated Key Exchange

let mut rng = rand::rng();
 
// Initialize the key exchange structs
let mut alice = Uake::new();
let mut bob = Uake::new();
 
// Generate Keypairs
let alice_keys = keypair(&mut rng);
let bob_keys = keypair(&mut rng);
 
// Alice initiates key exchange
let client_init = alice.client_init(&bob_keys.public, &mut rng);
 
// Bob authenticates and responds
let server_send = bob.server_receive(
  client_init, &bob_keys.secret, &mut rng
)?;
 
// Alice decapsulates the shared secret
alice.client_confirm(server_send)?;
 
// Both key exchange structs now have the shared secret
assert_eq!(alice.shared_secret, bob.shared_secret);

§Mutually Authenticated Key Exchange

Follows the same workflow except Bob requires Alice’s public key

let mut alice = Ake::new();
let mut bob = Ake::new();
 
let alice_keys = keypair(&mut rng);
let bob_keys = keypair(&mut rng);
 
let client_init = alice.client_init(&bob_keys.public, &mut rng);
 
let server_send = bob.server_receive(
  client_init, &alice_keys.public, &bob_keys.secret, &mut rng
)?;
 
alice.client_confirm(server_send, &alice_keys.secret)?;
 
assert_eq!(alice.shared_secret, bob.shared_secret);

§Errors

The KyberError enum handles errors. It has two variants:

InvalidInput - One or more byte inputs to a function are incorrectly sized. A likely cause of this is two parties using different security levels while trying to negotiate a key exchange.
Decapsulation - The ciphertext was unable to be authenticated. The shared secret was not decapsulated

Structs§

Ake: Used for mutually authenticated key exchange between two parties.
Keypair: A public/secret keypair for use with Kyber.
Uake: Used for unilaterally authenticated key exchange between two parties.

Enums§

Infallible: The error type for errors that can never happen.
KyberError: Error types for the failure modes

Constants§

AKE_INIT_BYTES: Mutual Key Exchange Initiation Byte Length
AKE_RESPONSE_BYTES: Mutual Key Exchange Response Byte Length
KYBER_CIPHERTEXTBYTES: Size in bytes of the Kyber ciphertext
KYBER_K: The security level of Kyber
KYBER_PUBLICKEYBYTES: Size in bytes of the Kyber public key
KYBER_SECRETKEYBYTES: Size in bytes of the Kyber secret key
KYBER_SSBYTES: Size of the shared key
KYBER_SYMBYTES
UAKE_INIT_BYTES: Unilateral Key Exchange Initiation Byte Length
UAKE_RESPONSE_BYTES: Unilateral Key Exchange Response Byte Length

Traits§

CryptoRng: A marker trait for securely unpredictable infallible RNGs
Rng: Trait for infallible random number generators
TryCryptoRng: A marker trait over TryRng for securely unpredictable RNGs
TryRng: Base trait for random number generators and random data sources

Functions§

decapsulate: Decapsulates ciphertext with a secret key, the result will contain a KyberError if decapsulation fails
derive: Deterministically derive a keypair from a seed as specified in draft-schwabe-cfrg-kyber.
encapsulate: Encapsulates a public key returning the ciphertext to send and the shared secret
keypair: Keypair generation with a provided RNG.
public: Extracts public key from private key.

Type Aliases§

AkeSendInit: Bytes to send when initiating a mutual key exchange
AkeSendResponse: Bytes to send when responding to a mutual key exchange
Decapsulated: The result of decapsulating a ciphertext which produces a shared secret when confirmed
Encapsulated: Result of encapsulating a public key which includes the ciphertext and shared secret
PublicKey: Kyber public key
SecretKey: Kyber secret key
SharedSecret: Kyber Shared Secret
UakeSendInit: Bytes to send when initiating a unilateral key exchange
UakeSendResponse: Bytes to send when responding to a unilateral key exchange